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// Copyright 2019 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
///////////////////////////////////////////////////////////////////////////////
#ifndef TINK_SUBTLE_STREAMING_AEAD_ENCRYPTING_STREAM_H_
#define TINK_SUBTLE_STREAMING_AEAD_ENCRYPTING_STREAM_H_
#include <memory>
#include <vector>
#include "tink/output_stream.h"
#include "tink/subtle/stream_segment_encrypter.h"
#include "tink/util/statusor.h"
namespace crypto {
namespace tink {
namespace subtle {
class StreamingAeadEncryptingStream : public OutputStream {
public:
// A factory that produces encrypting streams.
// The returned stream is a wrapper around 'ciphertext_destination',
// such that any bytes written via the wrapper are AEAD-encrypted
// by 'segment_encrypter' using 'associated_data' as associated
// authenticated data.
static
crypto::tink::util::StatusOr<std::unique_ptr<crypto::tink::OutputStream>>
New(std::unique_ptr<StreamSegmentEncrypter> segment_encrypter,
std::unique_ptr<crypto::tink::OutputStream> ciphertext_destination);
// -----------------------
// Methods of OutputStream-interface implemented by this class.
crypto::tink::util::StatusOr<int> Next(void** data) override;
void BackUp(int count) override;
crypto::tink::util::Status Close() override;
int64_t Position() const override;
private:
StreamingAeadEncryptingStream() {}
std::unique_ptr<StreamSegmentEncrypter> segment_encrypter_;
std::unique_ptr<crypto::tink::OutputStream> ct_destination_;
std::vector<uint8_t> pt_buffer_; // plaintext buffer
std::vector<uint8_t> ct_buffer_; // ciphertext buffer
std::vector<uint8_t> pt_to_encrypt_; // plaintext to be encrypted
int64_t position_; // number of plaintext bytes written to this stream
crypto::tink::util::Status status_; // status of the stream
// Counters that describe the state of the data in pt_buffer_.
int count_backedup_; // # bytes in pt_buffer_ that were backed up
int pt_buffer_offset_; // offset at which *data starts in pt_buffer_
// Flag that indicates whether the user has obtained a buffer to write
// the data of the first segment.
// If true, Next() was not called yet, which implies that neither
// header has been written to ct_destination_, nor the user had
// a chance to write any data to this stream.
bool is_first_segment_;
};
} // namespace subtle
} // namespace tink
} // namespace crypto
#endif // TINK_SUBTLE_STREAMING_AEAD_ENCRYPTING_STREAM_H_
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